A bearing for use in an idler bearing which is used in auxiliary peripheral equipment of an automotive engine such as an idler pulley, for example, includes a sealing device which covers a space between an outer ring and an inner ring with an annular seal so as to suppress the intrusion of foreign matters such as water and dust into an interior of the bearing. In addition, since the bearing of this type needs to permit a relative rotation between the inner ring and the outer ring, an outer circumference of the seal is fixed to the outer ring, and a seal lip is provided on an inner circumference of the seal so as to be brought into sliding contact with the inner ring.
Since the idler bearing is used to rotate at high speeds, the seal lip needs to be a light contact type having a small amount of interference in order to prevent a sliding portion of the seal from being heated. Because of this, it cannot be said that a sufficient sealing property against water and dust which attempt to intrude from the outside is obtained only by covering the space between the outer ring and the inner ring with the seal, and it is difficult to suppress the entrance of water and dust into the interior of the bearing from the space between the seal lip and the inner ring.
Then, in order to increase the water resistance of the bearing, normally, a shield plate called a slinger is provided on an outer side of the seal so that the seal lip is prevented from being subjected to water and dust.
In order to increase the water resistance further, an axial lip is formed to extend axially outwards from the seal so that the axial lip can be brought into contact with the slinger, whereby a space between the seal and the slinger is closed.
For example, JP-A-2004-11732 (Patent Document 1) describes a bearing sealing construction in which a seal has an axial lip.
FIG. 14 shows a sealing construction which is almost the same as the bearing sealing construction described in Patent Document 1 and which comprises a seal main body 110 and a slinger 105. Formed on the seal main body 110 are a seal lip 120 which is brought into sliding contact with a portion which lies parallel to an axis on an inner circumferential side of the slinger 105 and an axial lip 112 which is brought into sliding contact with a portion which lies vertical to the axis of the slinger 105. Since this axial lip 112 is brought into contact with the slinger 105 so as to close a path along which foreign matters such as water and dust reach the periphery of the seal lip 120, the waterproofness and dustproofness of the bearing are increased, and a increase in the sealing performance of the bearing can be expected.